feat: adding usage information to the script

scripts/crondisable.sh

 #!/bin/bash
 
+usage() {
+  echo "Usage: $0 -d USERNAME to disable a user"
+  echo "Usage: $0 -e USERNAME to re-enable a user"
+}
+
+if [[ "$EUID" -ne 0 ]]; then
+  echo "This script must be run as root!"
+  exit 1
+fi
+
+if [ -z "$username" ]; then
+  usage
+  exit 1
+fi
 
 
 while getopts ':d:e:' OPTION; do